1. Field of the Invention
This invention relates in general to radio control transmitters and in particular to a novel transmitter in which radiation of harmonics is suppressed.
2. Description of the Prior Art
Reissue U.S. Pat. No. 29,525 which issued on Jan. 24, 1978 comprising a reissue of U.S. Pat. No. 3,906,348 which issued on Sept. 16, 1975 entitled "Digital Radio Control" in which the inventor is Colin B. Willmott and which is assigned to the Chamberlain Manufacturing Corporation, the assignee of the present application discloses a digital radio control comprising a transmitter and receiver wherein a plurality of switches may be set in a transmitter to pick a particular code which will be transmitted and wherein a receiver which is set to the same code will detect and actuate a control device as, for example, a garage door operator.
The Federal Communication Commission has been giving consideration to the issuance of a new set of rules and measurement procedures for governing both security alarm devices and garage door radio controls. These new sets of rules and measurement procedures establish higher fundamental emission limits than had previously been available for security transmitters and eliminate the security device duty cycle requirements. The FCC proposal establish lower emission limits for security receivers than had been previously been required and impose new limits on transmitters and receivers with respect to harmonic emissions and "forbidden bands". The Commission also propose the requirement that measurements be made above 1 Ghz and to limit emissions in forbidden bands to 125 microvolts/m above 1 Ghz. Since garage door operators operate in the 300-400 MHz bands, the proposed FCC requirements would be very expensive for manufacture of garage door controls.